Abstract: A high-speed modem operates at speeds as high as 64 kbps in both the downlink direction from a digital modem to an analog subscriber and at an increased speed in the uplink direction from the analog subscriber back to the digital modem. Known systems provide a 56 kbps connection in the downlink direction but only provide for as high as a 33.6 kbps connection in the uplink direction. The present invention centers on the development of apparatus, systems, and methods for remote-echo cancellation whereby signal processing in the modem endpoints is used to remotely cancel an echo component at the input to a network-interface's ADC. Heretofore, this echo component has limited the achievable uplink data rate. Hence the present invention enables symmetric 56 kbps modem connections using POTS lines or the POTS channel within a DSL when line conditions warrant.

Abstract: A two-step training method for the estimation filter in the echo cancellation (EC) path of the analog front-end (AFE) circuit for a modem, such as an asymmetric digital subscriber line (ADSL) modem. During the first step, the coefficients of a filter that is preferably equivalent to the combination of the EC path and the receive (RX) path in the AFE circuit are determined with the EC estimation filter held fixed and the transmit (TX) path in the AFE circuit disabled. During the second step, the TX path is enabled and the coefficients of the EC estimation filter are determined using the path equivalent filter generated during the first step. The two-step training method takes into account variations in the operating characteristics of components in the various processing paths in the AFE circuit to converge on satisfactory coefficients for the EC estimation filter within an acceptable number of training symbols.

Abstract: Even if received signals are highly cross-correlated, echoes can be effectively cancelled and no psychoacoustical problems arise. A received signal xi(k) (where i=1, 2, . . . , N) and an additive signal ai(k) are added together, and the added output is used to drive a speaker i and input into an echo cancellation filter 405i. The received signal xi(k) and the additive signal ai(k) are input into adaptive filters 401i and 402i, respectively. The difference between the sum of the outputs from all the filters 401i and all the filters 402i and an echo ym(k) is detected as an error em(k). The coefficients of all the filters 401i and 402i are updated to reduce the error em(k). When the error em(k) is made sufficiently small, the coefficients of the filters 402i are transferred to the filters 405i. The sum of the outputs from all the filters 405i is detected as an echo replica, and the difference between the echo replica and the echo ym(k) is output.

Abstract: The present disclosure describes an ultrasonically-calibrated fast-start adaptive echo canceller system. The system consists of at least one ultrasonic transducer for transmitting ultrasound signal and at least one ultrasonic receiver for receiving reflected ultrasound echo. The system also includes an echo pulse counter that operates constantly when the phone is on. The counter processes the reflected ultrasound echo from the ultrasonic receiver to determine optimum sets of ultrasonic delay and attenuation coefficients. A fast-start adaptive controller adaptively controls an algorithm stored in a random access memory to correlate sets of audio-frequency coefficients for transversal filter with predetermined sets of ultrasonic coefficients by using an ultrasound to audio-frequency conversion table. The resultant sets of audio-frequency coefficients are held on a stack.

Abstract: An enhanced near-end voice signal may be generated in a hands-free environment by receiving an audio signal, generating an estimated acoustic echo signal, and generating a processed signal by removing the estimated acoustic echo signal from the audio signal. A near-end enhanced spectrum is then determined, that has one or more ranges of contiguous frequencies over which the detector spectrum takes on its largest values, wherein the range of contiguous frequencies are those associated with a relatively high echo return loss in the processed signal. The processed signal is filtered in accordance with the near-end enhanced spectrum, thereby generating an enhanced near-end voice signal. The enhanced near-end voice signal may then be applied to any of a number of components that are intended to process near-end speech. For example, when applied to a voice activity detector, the amount of energy contained in the enhanced near-end voice signal is then measured.

Abstract: A hybrid echo suppresser and associated methods of use provide echo suppression in a bi-directional communications system, while minimizing desired-voice signal disruption. The hybrid echo suppresser includes a linear echo canceller (LEC), a non-linear processor (NLP), and a control circuit. The LEC operates on an echo-causing signal to produce an estimated-echo signal, which is subtracted from an input echo-containing signal, thereby producing an echo-cancelled signal. The NLP operates on this echo-cancelled signal to eliminate residual echo arising from system non-linearities. The control circuit repeatedly compares the echo-containing signal and the estimated-echo signal to determine if the echo-containing signal includes a desired-voice component. If not, the control circuit operates the NLP in an echo-voice mode having substantial signal attenuation.

Abstract: A compander circuit (20) for echo cancellation in telecommunications apparatus with an estimator module (21) for estimating an echo coupling and a delay of a line echo and a characteristic module (23) with an associated multiplier (24) for controlling the short-time output level of zout(k) as a function of the short-time input level of zin(k) is characterized in that at all inputs and outputs of the compander circuit (20), a plurality of N communications channels are applied and outputted, respectively, at an N-fold clock rate as compared with a single communications channel; that all memory units in the compander circuit (20) are designed as multiplexer-buffer-demultiplexer (MBD) units (30); and that a modulo-N counter (26) is provided which controls all MBD units (30) so that in each of the MBD units (30), always the same memory cell (351, 352, 35N) assigned to a particular communications channel is addressed.

Abstract: Full acoustic coupling and echo cancellation is provided in implementations where there is acoustic coupling between acoustic zones.

Abstract: A circuit arrangement for controlling audio signal transmissions for a communications system that includes a microphone and a video camera. The arrangement comprises a video processor configured and arranged to receive a video signal from the video camera, detect movement of an object in the video signal, and provide a motion-indicating signal indicating movement relative to the object. An audio processor is coupled to the video processor and is configured and arranged to modify the audio signal to be transmitted responsive to the motion-indicating signal. In another embodiment, a video signal processor is configured and arranged to receive a video signal from the video camera, detect mouth movement of a person and provide a mouth-movement signal indicative of movement of the person's mouth.

Abstract: Device and method of channel effect compensation for a telephone speech recognition system is disclosed. The telephone speech recognition system comprises a compensatory neutral network and a recognize. The compensatory neural network receives an input signal and compensates the input signal with a bias to generate an output signal. The compensatory neural network provides a plurality of first parameters to determine the bias. The recognizer is coupled to the compensatory neural network for classifying the output signal according to a plurality of second parameters in acoustic models to generate a recognition result and determine a recognition loss. The first parameters and second parameters are adjusted according to the recognition loss and an adjustment means during a training process.

Abstract: Residual echo components resulting from an adaptive echo canceler are minimized by employing a subband echo suppressor. The residual echo components are minimized by individually, controllably adjusting the echo suppressor attenuation level in each of the subbands to gradually attenuate echo peaks having a magnitude lower than a clipping threshold with the magnitude of the attenuation increasing for residual echoes of decreasing magnitude. Additionally, the threshold of suppression engagement is dynamically matched to the signal gain in the echo path for each subband. If the signal gain in a subband is high (strong echo), the suppressor must attenuate residual echo peaks in the subband of higher energy to maintain a constant quality of service.

Abstract: In a communication system (100), a first echo return loss through communication system (100) associated with a first call connection between a caller (111) and a first caller (114) is estimated. A second echo return loss associated with a second call connection between caller (111) and a second caller (112) is estimated. The call connection may be switching from the first call connection to the second call connection after estimating the first echo return loss, and from the second call connection to the first call connection after estimating the second echo return loss. Echo generated in the first call connection is cancelled based on at least the first echo return loss by an echo canceller in communication system (100) after switching from the second call connection to the first call connection.

Abstract: Method and system for delivering a message over a telecommunications network to a recipient comprising transmitting a message over the telecommunications network to the recipient when a predetermined energy/silence condition is detected, performing echo cancellation on a signal communicated from the telecommunications network, and monitoring the signal to detect the energy/silence condition.